Add Kotlin support

pom.xml

@@ -53,6 +53,16 @@
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   </properties>
 
+  <dependencyManagement>
+    <dependencies>
+      <dependency>
+        <groupId>org.jetbrains.kotlin</groupId>
+        <artifactId>kotlin-stdlib-jdk8</artifactId>
+        <version>1.3.61</version>
+      </dependency>
+    </dependencies>
+  </dependencyManagement>
+
   <repositories>
     <repository>
       <id>openrs2</id>
@@ -227,6 +237,11 @@
           <artifactId>jacoco-maven-plugin</artifactId>
           <version>0.8.4</version>
         </plugin>
+        <plugin>
+          <groupId>org.jetbrains.kotlin</groupId>
+          <artifactId>kotlin-maven-plugin</artifactId>
+          <version>1.3.61</version>
+        </plugin>
       </plugins>
     </pluginManagement>
     <plugins>
@@ -234,12 +249,69 @@
         <groupId>io.github.zlika</groupId>
         <artifactId>reproducible-build-maven-plugin</artifactId>
       </plugin>
+      <plugin>
+        <groupId>org.jetbrains.kotlin</groupId>
+        <!--suppress KotlinMavenPluginPhase -->
+        <artifactId>kotlin-maven-plugin</artifactId>
+        <!--suppress DifferentKotlinMavenVersion -->
+        <version>1.3.61</version>
+        <executions>
+          <execution>
+            <id>compile</id>
+            <goals>
+              <goal>compile</goal>
+            </goals>
+            <configuration>
+              <sourceDirs>
+                <sourceDir>${project.basedir}/src/main/kotlin</sourceDir>
+                <sourceDir>${project.basedir}/src/main/java</sourceDir>
+              </sourceDirs>
+            </configuration>
+          </execution>
+          <execution>
+            <id>test-compile</id>
+            <goals>
+              <goal>test-compile</goal>
+            </goals>
+            <configuration>
+              <sourceDirs>
+                <sourceDir>${project.basedir}/src/test/kotlin</sourceDir>
+                <sourceDir>${project.basedir}/src/test/java</sourceDir>
+              </sourceDirs>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
         <configuration>
           <release>11</release>
         </configuration>
+        <executions>
+          <execution>
+            <id>default-compile</id>
+            <phase>none</phase>
+          </execution>
+          <execution>
+            <id>default-testCompile</id>
+            <phase>none</phase>
+          </execution>
+          <execution>
+            <id>java-compile</id>
+            <phase>compile</phase>
+            <goals>
+              <goal>compile</goal>
+            </goals>
+          </execution>
+          <execution>
+            <id>java-test-compile</id>
+            <phase>test-compile</phase>
+            <goals>
+              <goal>testCompile</goal>
+            </goals>
+          </execution>
+        </executions>
       </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>